Silicone hydrogels have been prepared by polymerizing mixtures containing at least one silicone containing monomer and at least one hydrophilic monomer. Either the silicone containing monomer or the hydrophilic monomer may function as a crosslinking agent or a separate crosslinking agent may be employed. Various alcohols, including n-hexanol, ethanol, and n-nonanol have been used as diluents to compatibilize the silicone monomers and the hydrophilic monomers. However, the articles made from these components and diluents either did not form clear articles or were not sufficiently wettable to be used without a coating.
Primary and secondary alcohols having more than four carbon atoms have also been disclosed to be useful as diluents for silicone containing hydrogels. However, many of these diluents do not form clear, wettable articles when internal wetting agents are included in the reaction mixture. While these diluents are useful, many require an additional compatibilizing component to produce uncoated clear, wettable molded articles.
Compounds having specific Hansen solubility parameters and Kamlet alpha values have also been disclosed to be useful as diluents for silicone hydrogels. However, many are not miscible with water, requiring the use of complicated solvent and water exchange processes. Thus, there still remains a need in the art for silicone hydrogels which are polymerized in an economic and efficient way which may yield medical devices such as uncoated clear contact lenses with wettable surfaces.